Technical Field
Embodiments of this disclosure relate to a document reading device and an image forming apparatus including the same and more particularly, to an auto document feeder (hereinafter, simply referred to as an ADF) of a sheet-through system that is mounted on an image forming apparatus and is configured to enable dual-face reading of a document.
Description of the Related Art
For office equipment such as a multifunction peripheral (hereinafter, simply referred to as an MFP) on which an ADF is mounted, a user often leaves the office equipment in a state in which main power is supplied to the office equipment, such that the user can use the office equipment immediately when the user desires to use the office equipment. To reduce consumption power in a standby mode, the office equipment may have a function of automatically switching a mode into a low consumption power mode, that is, a so-called energy saving mode when a non-used state continues for a constant time or more.
In the energy saving mode, power for sensing is supplied to only an operation panel or a document set sensor of the ADF serving as a trigger when the user uses the office equipment, and other power supplies are turned off. In this way, in the office equipment according to the related art, the power supplies other than the power supply for the sensing are turned off in the energy saving mode, so that low power consumption is realized.
The office equipment in the energy saving mode returns to a normal operation mode in which a normal operation is enabled, through a course of, for example, “setting of a document on the ADF or detection of an operation of the operation panel”, “an initial operation of the office equipment including the ADF”, and “restart of the office equipment”. Accordingly, when the office equipment returns from the energy saving mode, a user waits for a time (hereinafter, also referred to as “energy-saving returning time”) until the initial operation of the ADF is completed.